I, too, came away with approval voting being my favored approach.
One question to ask yourself, though, is this: in an election where candidate A is loved by 55% of the population and hated by 40%, and candidate B is loved by no one, but tolerated by 80% of the population, who "should" win? It's more of a philosophical question, but depending how you answer it influences how you should choose a voting system.
If you think the 80% tolerated candidate should win, then approval voting is for you. If you think being loved by 55% of the population should be the winner, then IRV or another system may be better.
I personally prefer the boring, centrist 80% tolerated outcome, so I like approval.
Another thing I realized, is that a lot the research doesn't seem to take into account polls ahead of time and iterated preference making. Approval voting might be terrible if it's once-and-done, but if you have polls leading up to it, you can calibrate your "approval level" a little better.
E.g., if Hitler is running, you might say "I approve of everyone else". But if you see polls suggesting that no one is approving of Hitler, then you might raise your standards a bit and not approve of some more candidates.
Note that in practice, people start to vote tactically to prevent radical candidates, so there really isn't any voting system that works great for that purpose anyway.
I think the centrist option is probably the best for a number of reasons. I think a particularly bad president can do much more harm, than an unusually good president can do good. E.g. start WW3, or destroy the economy. Not to mention dividing the country and polarizing our political system.
Second there is a phenomenon called wisdom of crowds. That if you take the middle of the estimates given by a large number of uninformed people, it usually comes out very close to the true answer. The same should apply to voting. The middle preference of a large number of uninformed voters, should be close to optimal.
Third there are studies that show that centrists and moderates tend to have much more accurate beliefs than others. As in, their predictions of future events were the most accurate. Ideological people were extremely biased and inaccurate. That's probably the closest we can get to scientifically measuring how good their policies would be.
Lastly, for values questions, where there is no "right answer", the middle should be chosen. It's the fairest choice.
>Lastly, for values questions, where there is no "right answer", the middle should be chosen. It's the fairest choice.
As a radical, my problem with this is that the "middle" is defined by the power struggle between the "extremes": it always tracks the formerly "extremist" positions of the winning side. For instance, until last week, nobody would ever have said that privatizing Medicare was anything but extremist far-right lunacy. Coming this year, we're going to hear that it's a mainstream, centrist position. That's not even being said as a statement of fact, since it's transparently false -- people love Social Security and Medicare! It's being said as an imposition of hegemony on the part of the electoral winners, as how "we create our own reality now".
I'd expect Approval Voting to have the same property.